Many manufacturing situations require that thin, elongate objects, such as wires, pipes and rings be identified. In communication and electric power distribution systems, wires must be identified so that related subsystems can be correctly connected together. In hydraulic and pneumatic systems, hydraulic and pneumatic conduits often must be identified so that correct couplings can be made. While simple color coding can be used in some systems, other systems require more sophisticated identification, namely indicia identification that is usually alphanumerically based.
In the past, various methods for applying an indicia identifier to elongate objects, such as wires and pipes, have been proposed and used. Prior methods range from printing or embossing indicia directly onto the surface of the wire or pipe to applying a tag to the elongate object. Both of these methods and the apparatus associated with the methods have disadvantages. Printing or embossing indicia is expensive and time consuming, and cannot be used in some systems. For example, it is difficult to emboss or print readable indicia on wire bundles, including twisted wire pairs. Embossed indicia also have the disadvantage of being difficult to read, particularly under low light conditions.
While applying indicia bearing tags to thin, elongate objects overcomes the disadvantages of printing and embossing indicia onto such objects, prior methods of tagging thin, elongate objects have other disadvantages. In general, prior tagging methods use two distinct types of tags--cylindrical tags and flat, wrap-around tags. Both tags have the disadvantage that they are preprinted. Thus, a user must select the correct tag, as well as install it. In many situations, such as the application of tags to wire harnesses to be used in aircraft, the selection criteria requires the services of a relatively skilled employee. In the past, preprinted tags have also had the disadvantage that the indicia to be printed must be known well in advance so that the tags can be printed well prior to when they are to be applied. This makes an automated tag applying system difficult to create since manual intervention would be required each time an out of sequence, nonregular or delayed indicia tag is required.
Cylindrical tags have the further disadvantage that it is difficult to print indicia on a cylindrical surface. Further, cylindrical tags must be inserted from one end of an elongate object and slid to the desired position. In many instances this is difficult and/or time consuming, if not impossible. While wrap-around tags avoid the printing and positioning problems of cylindrical tags, in the past, wrap-around tags have had a protruding tab that creates other disadvantages. Specifically, some elongate objects, wires in particular, are frequently pulled through small holes. Sometimes the holes are located in inaccessible, or difficult to access, locations. Protruding tabs formed of weak materials are likely to be torn off when wires are pulled through such holes. Protruding tabs formed of strong materials prevent wires from being pulled through such holes as a result of the tabs impinging on the structure surrounding the holes through which the wires are to pass. Further, in the past, wrap-around tags have usually been held together by an adhesive. Adhesives have several disadvantages. They are frequently unreliable in long service-life environments. Further, many adhesives loosen and separate at elevated temperatures, and when exposed to a variety of solvent and/or corrosive fluids.
As a result, there is a need for a method and apparatus for applying easily readable indicia to thin, elongate objects, particularly an inexpensive method and apparatus. The invention is directed to providing such a method and apparatus.